NEW YORK—Signed for $1.1 million in 2007, outfielder Kelvin De Leon has provided the Yankees with diminishing returns on their investment. His OPS has dropped nearly 250 points from .888 in his 2008 pro debut to .647 a year ago with short-season Staten Island.

The 20-year-old Dominican still has time on his side. De Leon is built like an NFL safety at 6-foot-3, 200 pounds, with power to spare. Just as importantly, he has farm director Mark Newman in his corner.

"Like several kids from Latin America and the Dominican Republic, he has the type of skill set that includes big power and a strong arm," he said. "It will come down to him making consistent contact and smoothing his swing."

This offseason, the righthanded-hitting right fielder spent considerable time at the Tampa minor league complex. In between two stints there, De Leon participated in the organization's instructional program in the Dominican Republic.

The common thread between the two sites was De Leon launching balls in batting practice.

"We invested in his power," Newman said. Asked if De Leon had former New York farmhand Willy Mo Pena-type power, the farm director hesitated.

"We aren't going to see anything like that," he said. "But (De Leon) projects to have well-above-average major league power."

De Leon batted .236/.288/.359 with six homers in 259 at-bats last season, and with an unwieldy ratio of walks (17) to strikeouts (80). In fact, his strikeout total ranked third in the New York-Penn League.

"There were a lot of college pitchers in the league with the ability to spin the ball," Newman said. "Our coaches have worked with him daily, and we will see how it goes. This will be an interesting year. He will play at (low Class A) Charleston and that will be a good challenge."

YANKEE DOODLES

• The Yankees promoted manager Tom Slater from the Rookie-level Gulf Coast League to Staten Island. He replaces Josh Paul, who moved to the scouting department.

• The Yankees traded Double-A righthander Adam Olbrychowski to the Nationals for Justin Maxwell, a strong defensive outfielder who hits with power from the right side. In that regard, Maxwell resembles other recent acquisitions such as Greg Golson (minor trade with Rangers), Jamie Hoffmann (2009 Rule 5 draft) and Jordan Parraz (offseason waiver claim).